The invention relates to a height-adjustable support for a vehicle, in particular a semi-trailer. In the front region of a semi-trailer, there are generally fitted in pairs supports which can be adjusted in terms of height in order to support the semi-trailer when it is decoupled from the traction machine thereof. Known supports can be deployed in a so-called rapid operation into their support position and retracted into the transport position. This is generally carried out by means of a crank handle which is fitted to the support and which drives by means of a gear mechanism a spindle which extends inside the support. It is further often necessary during a mounting operation to raise or lower the semi-trailer under load, for example, as a result of unevenness of the ground or mutually different heights of different traction machines. In this case, the drive mechanisms of known supports have a load gear which has a higher reduction ratio than the high-speed gear. The raising or lowering operation under load is also generally carried out manually by means of a crank handle which is arranged on the support.
Height-adjustable supports of the known type are described, for example, in EP 2 163 444 A1 or DE 20 2009 009 952 U1.
In order to reduce the operational complexity when lifting or lowering the semi-trailer, it is additionally known to provide a motorized drive unit for deployment and retraction of the support. An arrangement of a motor on support winches mounted in pairs is described in DE 102 41 905 A1. In this instance, a motor engages with the drive shaft thereof on a connection shaft between two support winches and is supported on a component which is fixed relative to the motor. In addition, a crank handle is provided in order to be able to manually retract and deploy the support winches in the event of a failure of the motor. The connection shaft which is arranged and driven between the two support winches is already located, starting from the crank drive at the gear mechanism with a large step-down translation, in terms of force path in a high load moment range. In the further force path to the jack screw drive of each support only a small reduction is carried out in each case by means of a bevel gear stage. The motor which is arranged on the connection shaft between the support winches therefore has to be configured for a high torque, which is indicated in the document mentioned to be from 5 to 15 Nm. Furthermore, the assembly of the motor below the semi-trailer may also be difficult.
An object of the invention is to provide a height-adjustable support for a vehicle, which is simple to retract and deploy and which is constructed in the most robust manner possible.